Brake Fluid Shelf Life

[cal scott]

Preparing to do a brake fluid change since its been about two years since my last. At the time of my last change, I purchased two bottles of EBC dot 4 fluid but only used one. The second has been sitting, unopened since that time.

What is the general consensus on shelf life for unopened brake fluid? This particular product did not come with a foil seal - it relies only the lid to keep out the environment. I don't know if that is a factor.

 

[stangmx13]

IIRC, shelf life unopened is 2yrs. but id still use it on a street bike. dont expect it to last another 2yrs in the bike.

 

[kuksul08]

It depends. The brake fluid will be absorbing water through the container though at an extremely slow rate. I imagine a plastic container (most common) would be more permeable than a metal container (such as ATE brand). It also depends on the humidity and temperature where it's stored as this will affect the osmotic rate.

It's probably fine. I would use it in a street bike like stang says. If you're looking for absolute maximum performance for a racing situation then you want to seek out fresh fluid and go with RBF660 or something.

 

[msethhunter]

Use the shit out of it! It's been in a sealed container. 99% of riders can't even get DOT3 hot enough for it to be an issue.

 

[FreeRyde]

I have scattered bottles of brake fluid around my garage. I use them when I find them at random.

My brakes feel decent 73% of the time.

 

[295566]

Use the shit out of it! It's been in a sealed container. 99% of riders can't even get DOT3 hot enough for it to be an issue.

:afm199

If the drag racing dude says it's good, good enough for me :thumbup

 

[stangmx13]

I have scattered bottles of brake fluid around my garage. I use them when I find them at random.

My brakes feel decent 73% of the time.

I did that one time with a bottle I was sure was still good - my sharpie date wiped off . turns out it wasn't good and the brakes would go spongy at the end of a club race. I flushed the system 3x with new fluid with no improvement. In the end, draining the system entirely and reassembling with new fluid was required.

 

[bikewanker]

I have scattered bottles of brake fluid around my garage. I use them when I find them at random.

My brakes feel decent 73% of the time.

I’ll trade you a lightly used V Strom front Stinko for a brake fluid flush.

 

[Busy Little Shop]

Regardless of date always check for any moisture contamination by the color of the fluid... 100% moisture free is desirable...

Understanding Brake fluid

DOT 3 DOT 4 and DOT 5.1 are Glycol based brake fluids whereas DOT 5
are Silicone based... Glycol based fluids are designed to signal
moisture contamination by changing color... the fluid will start to
turn golden, then light brown, then dark brown indicating that it has
absorbed progressively more moisture. Eventually, if left unchanged
beyond the recommended service interval, the fluid will become dark
and yukky, indicating high amounts of water absorption and thus badly
contaminated fluid... user friendly Glycol based fluids also reduce
the effect of both corrosion and compressibility because it is not
only designed to accept significant amounts of moisture, but even to
neutralize it by dispersing this moisture evenly throughout the
system, thus preventing its concentration in any one area...


Boiling point of Glycol based brake fluids
DOT 3 205 °C (401 °F)
DOT 4 230 °C (446 °F)
DOT 5.1 270 °C (518 °F)

DOT 5 Silicone based fluid will not turn color to signal moisture content...

 

[splat]

Most people go decades on the same brake fluid in their cars...you'll be fine.

 

[anytwowilldo]

Most people go decades on the same brake fluid in their cars...you'll be fine.

May not be true. Braking systems on motorcycles are much smaller than those on cars and may not have capacity to deal with boiling fluid.

Somewhat recently I purchased a used KTM Dual sport. On my first off road outing at Hollister I completely lost the rear brake, without warning, sending me off the trail. By the time I got the bike back on the trail the rear brake was perfect, so I took off again. I thought I may of missed the pedal or something. A few minutes late the brake failed again -pedal through its stroke- no braking.
Turns out the brake fluid had absorbed too much water and it would boil at a very low temp, then the rear brake would fail. A flush with new fluid cured the problem as expected. I'm glad I was not pushing a sport bike into a corner at 100 MPH.

If you don't push your braking systems near the limits, use your fluid from a sealed container. If you do, go spend 10 bucks and buy new.

 

[bobl]

Regardless of date always check for any moisture contamination by the color of the fluid... 100% moisture free is desirable...

Understanding Brake fluid

DOT 3 DOT 4 and DOT 5.1 are Glycol based brake fluids whereas DOT 5
are Silicone based... Glycol based fluids are designed to signal
moisture contamination by changing color... the fluid will start to
turn golden, then light brown, then dark brown indicating that it has
absorbed progressively more moisture. Eventually, if left unchanged
beyond the recommended service interval, the fluid will become dark
and yukky, indicating high amounts of water absorption and thus badly
contaminated fluid... user friendly Glycol based fluids also reduce
the effect of both corrosion and compressibility because it is not
only designed to accept significant amounts of moisture, but even to
neutralize it by dispersing this moisture evenly throughout the
system, thus preventing its concentration in any one area...


Boiling point of Glycol based brake fluids
DOT 3 205 °C (401 °F)
DOT 4 230 °C (446 °F)
DOT 5.1 270 °C (518 °F)

DOT 5 Silicone based fluid will not turn color to signal moisture content...

It should be mentioned that 5.0 is NOT COMPATIBLE with dot 4, 3, or 5.1. Whoever designated 5 and 5.1 is an idiot. I witnessed a parts guy at a dealership extolling the virtues "this new 5.1" to a customer whose bike required dot4. Recipe for disaster. Why not 4.5, 6.0. or something that won't be confused with 5.1. Get a job in an office, make dumb decisions without real world knowledge, and break your arm patting yourself on the back.

 

[stangmx13]

DOT ratings are minimum boiling points. high quality DOT4 brake fluids generally exceed the minimum and some likely exceed DOT5.1 as well. Castrol SRF is the best fluid I know of. its "only" DOT4 and has a dry/wet boiling points of 590F/518F. notice the wet point is equal to dry DOT5.1. perhaps Castrol labels it DOT4 to avoid the stupid 5/5.1 confusion.

 

[Busy Little Shop]

It should be mentioned that 5.0 is NOT COMPATIBLE with dot 4, 3, or 5.1.

Mercy I thought I did... thanks for pointing that out...

WARNING: Dot 5.1 glycol (yellow) and Dot 5 silicone (purple) will not mix.

Note: DOT 5 silicone was created at the request of the military for
use in vehicles that are required to be parked for years at a time and
be ready for deployment. Harley-Davidson used DOT 5 until a decade ago
because it would not negatively affect paint but currently specifies
DOT 4 or 5.1

 

[Free_Bird]

If it gets old and don't want it to go to waste. Mark over the label and write "Paint Stripper".

 

[NorCalBusa]

You could do all of the various/calculated things- or just throw that shit out, get new and don't worry about it.

 

[ThinkFast]

AFAIK, the issue with “old” or previously opened brake fluid is it absorbs moisture (aka, it’s hygroscopic). As it absorbs moisture its boiling point is reduced, and when it boils it produces water vapor (steam), which, unlike fluid, is compressible. This compressibility is what causes your bakes to feel mushy. (Water in brake fluid is also responsible for causing corrosion in steel brake lines and components, which gums them up).

Therefore, the key to evaluating brake fluid is being able to measure how much moisture is in it. The good news is there is a low-cost tool for that. Get yourself a brake fluid checker for about $9 on Amazon or at your local parts store, like this one https://www.amazon.com/gp/product/B07QZ2LD1T/ and go to town.

 

[Escape pod]

Brake-fluid in the reservoir on the right needs changed (visible moisture denoting by darken brake fluid).

 

[Beanzy]

I'm cheap. So after opening a bottle of brake fluid, I'd encase the bottle in nitrile (or whatever they're made of) gloves.

As far as I could see, months later the opened brake fluid seldom showed any discoloration (moisture).

 

[Starpower]

AFAIK, the issue with “old” or previously opened brake fluid is it absorbs moisture (aka, it’s hygroscopic). As it absorbs moisture its boiling point is reduced, and when it boils it produces water vapor (steam), which, unlike fluid, is compressible. This compressibility is what causes your bakes to feel mushy. (Water in brake fluid is also responsible for causing corrosion in steel brake lines and components, which gums them up).

Therefore, the key to evaluating brake fluid is being able to measure how much moisture is in it. The good news is there is a low-cost tool for that. Get yourself a brake fluid checker for about $9 on Amazon or at your local parts store, like this one https://www.amazon.com/gp/product/B07QZ2LD1T/ and go to town.

That is a cool fluid checker and a great price! However, if color is an accurate indicator then even 9 bucks is too much and you don't need to open the reservoir to let in moisture. Anyone know how useful color is? I have a 4 year old 1/2 used can and it is still crystal clear.